This study is designed to describe the safety, tolerability, immunogenicity, and pharmacokinetics of escalating, repeated IM injections (the intended route of administration for immunoprophylaxis) of MEDI-524, initially in children £6 months old with a history of prematurity (³32 to £35 weeks gestation, without BPD), one of the target populations of infants at high risk for serious RSV disease.